Sunday, April 22, 2007

You've probably used that expression at one time or another: I need to sleep on it. Perhaps you understood intuitively that there was really something to be gained by literally sleeping before making an important decision. Or maybe you were just postponing having to decide. In either case, it's now been demonstrated that sleeping on it really does work.

Researchers at Beth Israel Deaconess Medical Center (BIDMC) and Brigham and Women’s Hospital (BWH) have found that understanding the big picture, seeing connections between disparate pieces of information, depends very strongly on taking a mental break from learning, and even more importantly, getting a good night's sleep.

“Relational memory is a bit like solving a jigsaw puzzle,” explains senior author Matthew Walker, PhD, Director of the Sleep and Neuroimaging Laboratory at BIDMC and Assistant Professor of Psychology at Harvard Medical School (HMS). “It’s not enough to have all the puzzle pieces – you also have to understand how they fit together.”

Adds lead author Jeffrey Ellenbogen, MD, a postdoctoral fellow at HMS and sleep neurologist at BWH, “People often assume that we know all of what we know because we learned it directly. In fact, that’s only partly true. We actually learn individual bits of information and then apply them in novel, flexible ways.”

For instance, if a person learns that A is greater than B and B is greater than C, then he or she knows those two facts. But embedded within those is a third fact – A is greater than C – which can be deduced by a process called transitive inference, the type of relational memory that the researchers examined in this study.

Earlier research by Walker and colleagues had shown that sleep actively improves task-oriented “procedural memory” – for example, learning to talk, to coordinate limbs, musicianship, or to play sports. Because relational memory is fundamental to knowledge and learning, Walker and Ellenbogen decided to explore how and when this “inferential” knowledge emerges, hypothesizing that it develops during “off-line” periods and that, like procedural memory, would be enhanced following a period of sleep.

Hey, anything that justifies getting more sleep is fine by me.

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